Measure ball lightning with published data

What was measured

In 2007, Paiva and colleagues reported luminous balls lasting seconds after electrical discharges in pure silicon. They interpreted the result using a model in which silicon vaporizes and then oxidizes.

Cen, Yuan and Xue recorded a natural event in Qinghai in July 2012. Its light lasted 1.64 seconds and showed silicon, iron and calcium emission lines. During its stable phase, the apparent luminous diameter was about five metres: the width of the brightness profile at half its peak. That is not a measurement of the object's physical diameter. Its average speed across the camera's view was about 8.6 metres per second; motion toward or away from the camera was not included.

Plasma sizes and timescales

These sources report different quantities: plasma radii, light-emitting size, confinement times and observation durations. Select an entry to see what each number describes.

Entry

The dense plasma focus plasmoidThe sheared-flow Z pinch columnNatural ball lightning, with a spectrumBall lightning seen by trained observersShoulders' charge cluster

Natural ball lightning, with a spectrum

For this July 2012 Qinghai event, the plotted five metres is the apparent luminous diameter during the stable phase, not the physical diameter. The recorded light lasted 1.64 seconds; its spectrum contains silicon, iron and calcium.

Apparent luminous diameter

5 m

Stable phase, approximately

100 nm1 mm100 m

Recorded light

1.64 s

Entire recorded luminous process

0.1 ns100 µs1,000 s

Read the sheet behind these figures

Work with the published figures

Open Figures 3 and 4 in the 2014 paper. Read several points from the apparent-diameter curve and mark the stable and fading portions. Label your estimates as readings from a published graph, with the units shown. Then list the elements identified in the spectrum. Which measurements describe the light's extent, and which identify emitting atoms?

For comparison, read the 2007 experiment's abstract. Record what it actually reports about duration and material. Keep unreported quantities blank instead of treating visual resemblance as a measurement.

Any new discharge experiment belongs in a professional institutional laboratory with a formal safety review. A proposed study could compare time-resolved spectra and lifetimes while controlling material composition. Agreement would help test a proposed mechanism; the single natural event cannot establish how all ball lightning forms.